PVC (Permanent Virtual Circuit) communications are set up in switched networks by a network manager. For PVC communications, the network manager determines a path for each call and configures each node along the path to set up all of the connections.
SPVC (Soft Permanent Virtual Connection) communications are also set up by a network manager. However, in this case, it is the nodes within the network that determine the path of a call rather than the network manager. There is more than one way to provision a SPVC call. In Dual Endpoint SPVC, the network manager configures both the source node and the destination node for a call. In Source Only SPVC, the network manager only configures the source node.
Multiple endpoint path (MEP) for providing endpoint redundancy for point-to-point communications is available for point-to-point PVC and SPVC communications. Selected calls on active end nodes in a digital communications network are configured by a network management system to have compatible alternate endpoint paths. When one of the selected active endpoint paths fails, the network management system automatically switches the endpath from the previously active endpoint to the alternate end point path. An example is disclosed in U.S. Pat. No. 6,498,779.
When an endpoint fails in a PVC call, in order to switch a call to an alternate endpoint, the network manager determines the new path, tears down only those connections not necessary in the new path, and establishes any new connections needed from the alternate endpoint to the old path. When an endpoint fails in a SPVC call, in order to switch to an alternate endpoint, the entire call must be torn down and re-established from the alternate endpoint. At the network element level, when a network element receives a message to tear down a particular call, it disconnects any connections on which the call to be torn down is the only call. Any shared connections remain connected in order to support the other calls going through those connections.
Point to Multipoint (P2MP) calls are typically used for broadcast video and long distance learning applications. A P2MP group is comprised of multiple calls from a root endpoint to multiple destinations (also referred to as leaf endpoints) in which the same data is sent. The calls all share the same resources until a point of divergence is reached. At points of divergence the data is sent to multiple leaf paths. P2MP is available for both PVC and SPVC. In PVC, P2MP calls can have MEP enabled.